As a technology for suppressing melting of toner, which is caused by a continuous high-speed rotation of a developing roller in a high-temperature environment, there is known a technology for reducing a rotational speed of the developing roller in a case where a temperature inside an image forming apparatus becomes a high temperature during printing of a print job.
However, when the rotational speed of the developing roller is reduced during the printing of the print job, there occurs a difference in an image quality of the print job between a print result before the rotational speed of the developing roller is reduced and a print result after the rotational speed of the developing roller is reduced. Accordingly, there is a possibility that the unity in the image quality of the print job is lost.